Art of separating suspended particles from gases



E. ART OF SEPARATING SUSPENDED PARTICLES FROM was.

MULLER.

- KPPLICATLON FILED AUG.-H, 19H.

, Patented Nov. 2, 1920.

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E. MOLLER. ART OF SEPARATING SUSPENDED PARTICLES FROM GASES. APPLICATIONmen AUGJI, 1911.

'1 57,466, Patented Nov. 2, 1920.

2 SHEETS-SHEET 2- UNITED STATES PATENT OFFICE.

ERWIN MGLLER, 0F BRACKWEDE, GERMANY, ASSIGNOR, BY MESNE ASSIGNMENTS, TO

THE CHEMICAL FOUNDATION, INC., A CORPORATION OF DELAWARE.

ART OF SEPARATING SUSPENDED PARTICLES FROM GASES.

Specification of Letters Patent.

Patented Nov. 2, 1920.

Application filed August 11, 1911. Serial No. 643,568.

1 '0 all'whomit may concern:

Be it known that I, ERWIN citizen of the Empire of Germany, and asubject of the Kin of Prussia, residing at Brackwede, in the Trovince ofWestphalia, Germany, have invented certain new and useful Improvementsin the Art of Separating Suspended Particles from Gases, of which thefollowing is a specification.

This invention relates to electrical separation ofsuspended matter fromgases, and the main object of the invention is to perform' thisoperation in an efiicient and thorough manner. It is a distinctivefeature of the present invention that the separation of the suspendedmatter is performed by a series of successive operations, wherein theparticles are first charged and then sub- -jected to the action ofelectrostatic fields of progressively increasing effectiveness, so thatthe suspended matter is removed in stages. I

Anbther object of the invention is to subject the particles which havebeen charged by ionization of the gas, to electrostatic fields forreinforcing and supplementing the action of the ionizing electrodes, incausing separation of the charged particles.

The accompanying drawings illustrate an apparatus suitable for carryingout my invention, and referring thereto:

Figure 1 i a vertical section of the apparatus, on line Y. Y. in Fig. 2.

Fig. 2 is a horizontal section on line X. X. in Fig. 1.

Fig. 3 comprises a schematic view of my apparatus.

In the present invention, as carried out in the apparatus illustrated inthe drawing, it is assumed that the gases carrying the uspendedparticles enter, and pass through, a conduit or passage X, in thedirection shown by winged arrows in Fig. 2, and are subjected in saidconduit, to the action of elec-[ tric fields, to cause separation ofsuspended matter therefrom. Conduit X preferably increases in capacity,or cross-section, from the entrance to the exit for the gases, so thatthe gases entering the conduit at a certain velocity, are reduced invelocity as they pass through the conduit.

Within, the conduit X are provided electrodes arranged in sets AVB. C.and 1)., located so as to act successively on M6LLER, a 4

the gases passing through the conduit. Such electrodes comprise chargingelectrodes 1 1", 1, for producing electric fields for charging thesuspended particles, 3*, 3, 3, for producing electrostatic fields forcausing separation of the charged particles from the gases, andelectrodes 2, 2 2, and 2, for cooperating with the aforesaid electrodesto produce the charging and electrostatic fields.

Electrodes 2, 2 2, and 2 of the respective sets may consist of platessupported by bars 10 extending across the conduit and supported on thewalls thereof, said bars being conductors and connecting said electrodesto one side of the charging circuit, for example to ground, in case of aground ed circuit; the conduit X in that case bein of conductingmaterial and being grounde as shown at 12.

The charging electrodes 1, 1 1 are adapted to promote ionization of thegases adjacent thereto consisting, for example, of rods 1*, havingpointed projections as shown in set 1A., or of fine wires 1, 1, asshown. in sets B. and C. These wires may be covered or coated, andinstead of wires any linearly extending electrodes, such as strips ofmetal of suitable thicknes and width, may be used.

'The function of the first set of electrodes is, to produce initialionization of the gases, and to cause separation of relatively largeparticles, such as fibers. Since, on the one hand, such large particlescan be readily electrified and thereby more readily removed from thegas, and, on the other hand, they are apt to clog the spaces between theelectrodes; the electrodes 1*", and 2 of the first set are placedrelatively far apart. Moreover, since uniformity of discharge is not soessential in this initial action, the electrodes of the form shown at 1may be used to advantage, as they are more readily maintained and keptclean than fine wires would be. The ionizing electrodes 1 of this setare shown as mounted on frame bars 14, one of which is supported by aninsulator 15 formed, for example, as a bushing in the top of conduit X,the connection 16 for supporting and leading current to electrodes 1being connected to top frame bar 14 and passing through this bushing.

In the second set B of electrodes, the space between the ionizingelectrodes l and the electrodes 2 is shorter than the correspondingspace in the first set, so as to distribute the charging efiect moreuniformly and effectively in the gas, and on account of the closerspacing and of the widening of the conduit X, the number of electrodesis increased so as to increase the efi'ective area of the ionizingelectrodes. This effective ness, both as to uniformity and as toincrease of area are also increased in this set B by use of the linearlyextended electrodes such as fine wires as shown at l, and by providinga'plurality of such wires arranged in parallelism opposite eachelectrode 2. These ionizing electrodes 1 are shown as suspended from-abar 17, supported in insulators 18 in the side walls of conduit K, saidbar 17 also supporting electrostatic field producing electrodes 3*,formed for example as rods or Wires of greater cross section than theionizing electrodes 1 and extending parallel thereto. The ionizingelectrodes are preferably arranged in rows, parallel to electrodes 2",the electrostatic field producing electrodes being at the ends of suchrows. By reason of the greater thickness of the rods 3* as compared withthe wires 1*, the

ionizing action of said rods is relatively slight, their function being,primarily, to reinforce or strengthen the electrostatic field forcausing migration of the charged particles. The reinforcing action ismore pronounced on the outer wires l of the rows than on theintermediate wires 1"", thereby approximating a more equal dischargefrom the several wires of the row. Another important use of the rods orthicker wires 3 is to protect the finer wires from injury or destructionin case of the .formation of electric arcs.

Suitable tensioning means, such as springs 7 or weights 8 are preferablyprovided for holding the ionizing electrodes in position. In case finewires are used as ionlzmg electrodes, vibration damping means may beprovided therefor consisting, for ex-' ample, of weights 34 attached towires at points where vibration is liable to be pronounced.

In the succeeding sets of electrodes the electrodes 1 and 2 are closertogether than in the preceding set, and the electrostatic fieldproducing electrodes 3 are adapted to produce a stronger reinforcingaction, said electrodes 3 being of relatively extended surface or areaand formed, for example, as plates carried by bars 20 mounted oninsulators 21 on side walls of conduit X, so as to alternate with andextend parallel to electrodes 2.

The last set of electrodes consists of elecelectrodes 2 cooperatingtherewith, said memes 'of the preceding set. The closeness of theelectrodes therefore increases progressively in successive sets, and thenumber of electrodes increases, both by reason of this closer Spacingand of the widening of the conduit X, so that the gases in passingthrough the conduit are subjected to more closely applied and moreextensive electrostatic field surfaces.

In some cases it may be desirable to roughen the electrode surfaces, orsome of them, or to impart to them a pubescent quality as indicated in2' and 3', Fig. 2, to in crease their effectiveness.

The number, shape and size of the electrodes in each set, and the numberof sets employed, will depend on the character of gases to be treatedand the percentage, kind and quantity of the suspended particlestherein, so that at any-stage of the method, a greater or less number ofany of the electrodes may be used, in parallel, or in series, and anynumber of steps may be combined in one or may be omitted if desired. Thevarious parts of the apparatus may also be electrode sets A, B, C and D,generally require different voltages and current, volta e and currentregulating devices 27*, 27", 2 and 27 may be interposed between the Wire28 leading from the high tension source 29, said devices consisting, forexample, of regulable resistances, such resistances also'Serving to makethe operation of the apparatusmore steady. In case a grounded circuit isused, one side of the source is grounded as at 31, the electrodes 23 ofeach set being also grounded through the walls of the conduit as abovedescribed, so as to complete an electric circuit including theelectrodes.

My method is carried out as follows:

The gas carrying suspended particles enter the conduit X in thedirection of the arrows and passes first between the electrodes 1 and 2of the first set, electrodes 1 being charged with high tensionelectricity from theqconnection 28 to the source 29-- ionization of thegas takes place adjacent to the pointed projections of said electrodes,with the result that the suspended particles become charged and migratetoward the electrodes 2 under the action of the electrostatic fieldexisting between electrodes 1 and 2. The coarser or larger particleswill be more effectually charged and are deposited or collected, inlarge measure on the electrodes 2 before the gas passes the first set ofelectrodes, the electrodes 2 being preferably extended a Considerabledistance beyond electrodes 1, in the direction of flow of the gas, toprovide more opportunity for collection of these heavier particles. Thegas, from which the heaviest particles have been removed then passesbetween the electrodes of the second set where it is subjected to a moreeffective separating action, by means of the closer spacing of theelectrodes and the greater area presented thereby causing a more uniformand effective distribution of the ionizing action in the gas, and byreason of the stronger ionizing action in the gas,and by reason of thestronger ionizing and displacing actions due to the strengthening of thefields.

In passing to this second set, the velocity of the gas is reduced, bymeans of the increase in cross section of the conduit, so that the timeduring which the gas is subjected tothe separating action iscorrespondingly increased. A further increase in precipitating effect issecured by the, electrostatic fields produced by the electrodes 3, whichserve to aid in forcing to the collecting electrodes 2", the particlescharged by the ionizing action of the fine wire electrodes 1*, as wellas the particles which have been charged in the first set A, but haveescaped therefrom without precipitation. By this means a further amountof suspended matter is removed and the gas then, passes to the next setC where it is subjected to the action of still more closely arrangedelectrodes and causing precipitation of a still further quantity ofsuspended'matter. The successive sets of electrodes of progressivelyincreasing effectiveness will, in general, have the effect of separatingthe suspended matter from the gas in stages, the larger particles, forexample, being separated in the first set of electrodes, somewhatsmaller or finer particles by the next set, and this operation may becarried on in as many stages as may be necessary, with a set ofelectrodes for each stage. After leaving the last ionizing electrodesthe gas may still contain charged suspended particles and in order toallow full opportunity for such particles to be collected the gas ispassed through the set D, wherein it is subjected to the action of anelectrostatic field for forcing the charged .particles against'theelectrodes 2. Any desired number of electrostatic field sets similar toset D may be provided through which the gas is passed after leaving setD or at any intermediate stages, after passing any one of the precedingsets A, B or C. The increasing cross section of the conduit as the oughseparation.

lVhat I claim is: 1. The method of separating suspended particles fromgases, which consists in subjecting the gas to the action of an ionizingdischarge of electricity to charge the suspended particles, and thensubjecting the charged particles to the action of an electrostatic fieldof progressively increasing strength.

2. The method of separating suspended particles from gases whichconsists in causing the gas to flow through an electrostatic field,discharging electricity into the gas while in said field, to charge thesuspended particles, and then passing the gas at a reduced velocity,through a stronger electrostatic field.

3. The method of separating suspended particles from gases, whichconsists in passingthe gas through electrostatic fields, dissaid fields,to chargethe suspen ed particles,

and then passing the gas in progressively increasing volume at lowerspeed through a plurality of electrostatic fields, each shorter than thefirst field but whereby a more effective electro static action isproduced throughout the body of the gas.

4. The method of separating suspended matter from gases which consistsin subjecting the gas successively to the action of electrostatic fieldsof progressively decreasing length, and of progressively increasingnumber whereby a more effective electrostatic action is producedthroughout the body of the gas.

5. The method of separating suspended particles from gases whichconsists in causing the gas to flow through an electrostatic field,discharging electricity into the gas while in said field, to charge thesuspended particles, and then passing the gas through electrotstaticfields of progressively increasing effectiveness.

6. The method of separating suspended particles from gases whichconsists in pass ing the gas through anelectrostatic field, dischargingelectricity into said gas while in said field, to charge the suspendedparticles, and then passing the gas through a plurality of electrostaticfields, each shorter than the first field.

7 An improvement in means for removing suspended particles from gaseousand fluid of a framework and a plurality of spaced apart Wires, and agrounded electrode having one face opposite said Wires, said Wires beinggrouped in a manner to produce and direct electromagnetic waves towardthe oncoming particle-laden gaseous or fluid fluid bodies comprising aplurality of platelike grounded electrodes, and a plurality of framesalternating With said electrodes and each provided with a plurality ofparallel attenuated electrode members.

10. An improvement in means for removing suspended particles fromgaseous and memes fluid bodies comprising spaced apart groundedelectrodes, spaced apart active electrodes each comprising aframecarrying a plurality of attenuated electrode members, and a tie rodconnecting the frames of said active electrodes.

11. In the art of producing electrical precipitation of particles fromfluid or gaseous streams, opposing electrode systems, the dischargesystem comprising a rigid frame, a support therefor, and a plurality ofdischarge producing elements rigidly carried by the frame and extendingin parallelism with each other on a common plane corre sponding to thedirection of flow of the stream, said frame and elements constituting aunit of single charge sign.

- In testimony that I claim the foregoing as my invention, 1 havehereunto set my hand in the presence of tWo subscribing Witnesses.

ERWIN MGLLER. Witnesses MICHAEL J. STARK, FRIEDA T. LEBENSTEIN.

